Various approaches have been pursued to achieve higher and higher burning rates of solid propellants used in the propulsion subsystems of ballistic missile interceptors. Some of these approaches have involved, as time as gone by, the use of progressively finer and finer-ground ammonium perchlorate, combustion catalysts, such as, ferrocenyl and carboranyl burning rate accelerators, and staples of aluminum, zirconium, and graphite. Although the burning rates achieved have been considered outstanding when compared to the prior art, the needs of future advanced terminal interceptors, especially those of the low altitude commit type, will require propellants having burning rates several times faster than those which are currently available.
Characteristics, such as, burning rate controllability, extinguishability, and a high pressure exponent were obtained through use of porous ammonium perchlorate in the specially-compounded solid propellant which was developed for a Controllable Solid Propellant Rocket Program. The results obtained from the use of porous ammonium perchlorate as a portion of the oxidizer in such a propellant resulted in a motor which had a start-stop and restart capability. This contributed significantly to the advancement of the state-of-the art of controllable, solid-propelled propulsion subsystems.
The compatibility of ammonium perchlorate and porous ammonium perchlorate with propellant ingredients has been well established in composite propellant formulations. The high burning rate level which could be achieved by using porous ammonium perchlorate was not assessed since the emphasis has been on the use of more and more finely-ground ammonium perchlorate to provide the major increase in the propellant's burning surface area, and thus achieve the necessary ultrahigh burning rates.
The processing and dispersing problems of high solids loadings propellants have been well recognized. A major problem attendant with the use of the ultrafine ammonium perchlorate, the agglomeration of the ultrafine ammonium perchlorate, has pointed out the need for other approaches which must be pursued in order to raise the burning rates of composite modified double-base propellants required for future advanced terminal interceptors which may use these propellants.
Therefore, an object of this invention is to provide a solid composite modified double-base propellant composition which employs porous ammonium perchlorate oxidizer to achieve an ultra-ultrahigh burning rate for the propellant composition.
Another object of this invention is to provide an ultra-high burning rate composite modified double-base propellant composition which employs about 34 to about 38 weight percent porous ammonium perchlorate to achieve a more than twofold increase in the burning rate without the employment of a special burning rate catalyst.